Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/29/20

Area Forecast Discussion
National Weather Service La Crosse WI
1051 PM CDT Tue Apr 28 2020 .UPDATE... Issued at 309 PM CDT Tue Apr 28 2020 A narrow window remains for severe weather in far southwest Wisconsin, though it appears to be slowly closing. Latest satellite imagery shows high clouds remaining in place over the area, preventing the instability necessary for storms from building in. That said, should something be able to get going in that area, southeasterly surface flow would lead to looping hodographs in the 0- 3 km layer and thus, a threat for some rotating updrafts. Farther to the west, surface flow becomes southwesterly just ahead of a cold front located along a line containing Rochester, MN, and Charles City, IA. These areas saw some brief clearing earlier which allowed for upwards of 1000 J/kg of SBCAPE to build, but the southwesterly flow really limits low level shear, so the severe weather probability there would be quite low. So bottom line, the overlap between the most favorable shear and instability is quite narrow, which is limiting the overall severe weather potential. Can`t completely rule out something still happening in far southwest Wisconsin over the next few hours, but once surface flow becomes southwesterly (and eventually northwesterly behind the cold front), the potential will decrease to near 0. && .SHORT TERM...(This Afternoon through Wednesday) Issued at 103 PM CDT Tue Apr 28 2020 For early this afternoon, the line of showers and scattered storms will continue to move east into central Wisconsin. Behind this line, some partial clearing was evident in the satellite data in north-central Iowa. Still some questions on how much of this clearing will move into our area this afternoon. Another question is how much low level moisture can work north into the area ahead of the cold front. Currently have dew points in the lower and mid-50s. However, with dew points closer to 60 across central Iowa, we expect to see our dew points south of I-90 to approach 60 degrees by mid to late afternoon. Both the solar insolation and dew points will have an impact on the amount instability which will build across the region this afternoon and early evening. The latest HREF mean continues to suggest that surface CAPES will climb into 500 to 1000 J/kg from mid afternoon into early evening. The RAP continues to be the most robust with CAPES of 1250 to 1750 J/kg. One development in the models this morning is that the best instability and shear are some what disjointed from each other. This may have impact on how widespread the supercells will be across our area. It still looks like some will develop, so thinking we will see some large hail and damaging winds along and just ahead of the cold front. There is still a possibility of isolated tornadoes near the warm front which be located near the Interstate 90 and 94 corridors. The greatest severe weather threat looks to be from 3 to 8 PM. From late tonight into Wednesday, the combination of steep 1000 to 850 mb lapse rates and tight surface gradient will result in sustained northwest and north sustained winds of 15 to 30 mph with gusts of 30 to 45 mph. .LONG TERM...(Wednesday night through Tuesday) Issued at 103 PM CDT Tue Apr 28 2020 On Wednesday night and Thursday, ridging will build into the region at the surface and aloft. 850 mb temperatures will gradually warm from 4.5-7.5C on Thursday to 9-12C on Friday. High temperatures will be in the lower and mid-60s on Thursday and range from mid-60s to lower 70s on Friday. On Friday night and Saturday, a short wave trough will move along the northern periphery of the ridge. As this occurs, the ridge will flatten. Like the past couple of days, the models continue to struggle on whether precipitation will develop along and ahead of the warm and cold fronts. The GFS is the most robust with developing precipitation. Meanwhile, the Canadian produces no precipitation for the area. Due to these difference, stayed closed to the NBM model blend for precipitation. With 850 mb temperatures surging into the 10-14C range ahead of the cold front expect surface temperatures to range from the mid-60s to lower 70s. From Saturday night into Monday, an upper level trough develops across the Upper Mississippi River Valley and Great Lakes. Northwest wind aloft will bring progressively cooler air into the region. 850 mb temperatures will range from 0-6C on Sunday and then only range from -3 to 3C by Monday. High temperatures will be in the 60s on Sunday and range from the mid-50s to mid-60s on Monday. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1051 PM CDT Tue Apr 28 2020 With the cold front well past both airports, all the showers have temporarily moved out of the area. A few more are possible overnight into Wednesday morning as a trough of low pressure rotates around the main area of surface low pressure. These may bring in some light rain to KLSE without any visibility restrictions while primarily staying west of KRST. Ceilings have already come down to IFR/MVFR and not expecting much change to occur until late Wednesday afternoon when heights should go up to VFR. Some potential for the clouds to scatter out Wednesday evening but confidence not high enough to detail that at this point. The north winds have already become gusty at both sites. These gusts should increase into the 30 to 35 knot range late tonight and continue through much of Wednesday. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ UPDATE...CJA SHORT TERM...Boyne LONG TERM...Boyne AVIATION...04
Area Forecast Discussion
National Weather Service Bismarck ND
858 PM CDT Tue Apr 28 2020 .UPDATE... Issued at 853 PM CDT Tue Apr 28 2020 For this update, will let the wind headlines expire as scheduled at 02z. While breezy to windy conditions will linger over the next couple of hours, things should drop off rather quickly with the loss of daytime heating. Scattered to numerous showers continue across eastern portions of the forecast area, generally from the Turtle Mountains down through the James River Valley. As with the winds, this activity will begin to diminish rather quickly with the loss of heating. Observations show that lighting strikes have moved out of the forecast area and into eastern North Dakota so will take the mention of thunder out of the Hazardous Weather Outlook. Otherwise, just blended in the latest observation to the going forecast. UPDATE Issued at 624 PM CDT Tue Apr 28 2020 The forecast looks to be on track and just blended in the latest observations for this update. Will keep the headlines going as 60+ mph gusts have been observed over the last hour across various locations in the southwest where a High Wind Warning is still in effect with widespread Advisory criteria still being met elsewhere in the headline area. The strongest showers and thunderstorms have generally moved off into eastern North Dakota and diminished, but two narrow bands of showers with intermittent lightning strikes will continue to move through the area extending from the Turtle Mountains through the James River Valley over the next few hours. Chances of precipitation will quickly subside as the sun sets, around 03z to 06z. && .SHORT TERM...(This evening through Wednesday) Issued at 221 PM CDT Tue Apr 28 2020 The main concern in the short term period will be winds late this afternoon. It still looks like there may be a few hours (20-24 UTC) where winds could reach HWW criteria over the warned area. Although strong winds right off the surface are less than advertised earlier, RAP forecast soundings still hint at the potential for 50 knot winds aloft to work down to the surface from around Sidney to Baker MT and east to Watford City, Dickinson and Hettinger. Therefore will leave the RFW in effect through early evening, although the evening shift may be able to drop it a bit early. Winds do diminish in the west early this evening but the remain strong in the central portion of the state through the evening (but below advisory criteria). Late tonight as the surface low currently around Minot, pushes into eastern ND, wrap around moisture swings through central ND, keeping a chance of showers in the forecast through around midnight or even a little later around the Turtle Mountains and the James River Valley. Slight instability with CAPE values of 500-1000 j/kg will remain this afternoon and early this evening, perhaps into late evening around the James River Valley. We clear out in the west, behind the exiting system, with high pressure settling over the far west by 12 UTC Wednesday. This will bring cool overnight lows around 30 degrees west. The central will remain mainly in the upper 30s and lower 40s with lingering cloud cover. Much less wind and dry on Wednesday with highs in the 60s east to lower 70s west as upper ridging builds over the area. .LONG TERM...(Wednesday night through Tuesday) Issued at 221 PM CDT Tue Apr 28 2020 Midweek ridging over eastern Montana and the western Dakotas begins to break down on Thursday. Then a shortwave trough tracks across the state on Friday, bringing a chance of showers north and a slight chance south. Upper ridging then builds over the area through the weekend with sharp ridging developing over the Mondak region late Sunday. A stronger wave tracking around the base of a Northern Pacific trough moves through the Northwest U.S. Sunday and Monday, then develops into a closed upper low over the Northern Plains by Tuesday. There are some significant differences in placement and timing, but the ECMWF, GFS and GEM all show a closed circulation over the northern plains on Tuesday. The GFS ins the slowest and deepest, bringing the best chance for significant rainfall. The EC and GEM are more progressive. Except for some 80s on Thursday in the west. Temperatures look to be mainly in the 60s and 70s through the weekend, then cooling a bit early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 624 PM CDT Tue Apr 28 2020 Very windy conditions will gradually subside this evening as the sun sets. Shower and thunderstorm activity will also diminish with the loss of daytime heating. An area of MVFR ceilings may form along and east of the Missouri River after midnight, impacting the terminals of KBIS/KMOT/KJMS, but categories will once again improve to VFR categories by Wednesday morning. Otherwise and elsewhere, VFR conditions should prevail. && .BIS WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 9 PM CDT /8 PM MDT/ this evening for NDZ001- 019-020-034-042-045. High Wind Warning until 9 PM CDT /8 PM MDT/ this evening for NDZ009-017-018-031>033-040-041-043-044. && $$ UPDATE...ZH SHORT TERM...TWH LONG TERM...TWH AVIATION...ZH
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
926 PM CDT Tue Apr 28 2020 .UPDATE... In terms of grid updates have only made minor updates to shift precipitation for South Central Texas until after midnight. This fits in line with the most recent runs of the HRRR and other high resolution models. It looks like the best window for precipitation will be between 5 and 8 am. These recent runs of the HRRR also show the western flank of the squall line weakening slightly with the main bowing portion with the greatest severe wind risk focusing more in Houston`s area and possibly getting into our eastern counties like Lee and Fayette. If the recent HRRR runs and the 18z Texas Tech WRF verify the 30% PoP for Bexar County is too high and San Antonio may once again totally miss out on any precipitation. One probable reason for the storms weakening as they approach South Central Texas by Wednesday morning is the continued presence of a capping inversion still evident on evening aircraft soundings out of the AUS and SAT airports. While the advancing front should overcome that cap it may play a role in limiting some of the thunderstorm activity. Trends will certainly be monitored through the night, but as of now it looks like the greatest threat will be concentrated east of I-35 and possibly east of our area. SPC does have Severe Watch 154 across our northern border with the Fort Worth and Houston until 4 am. As stated earlier in the discussion storms should be approaching our northern border around then and any need for a watch at that point will be coordinated between SPC and EWX pending the radar and model trends early Wednesday AM. && .PREV DISCUSSION... /ISSUED 651 PM CDT Tue Apr 28 2020/ AVIATION... VFR conditions persist this afternoon across all of South Central Texas. Storms across Mexico are producing some cirrus blow off around K5T9 (Eagle Pass) but this is all south of Del Rio. VFR skies should continue through much of the night ahead of a front which will arrive early Wednesday morning. Precipitation chances will be greatest at AUS and so prevailing thunder has been included from 08z to 11z Wednesday AM. When the front arrives winds will switch around to the north and begin around 12 knots, but quickly pick up through the day Wednesday and be gusty at times up to 25 knots. The front will arrive around 11z at SAT/SSF. Models show much of the precipitation to the east and north of the San Antonio terminals so have only kept VCTS in for those areas. DRT should remain dry through the period with the front and north winds arriving around 09z. Ceilings could briefly drop to MVFR with the precipitation along the front, but VFR skies return by 15z across the I-35 corridor. PREV DISCUSSION... /ISSUED 219 PM CDT Tue Apr 28 2020/ SHORT TERM (Tonight through Wednesday Night)... A cold front will move down through North Texas tonight bringing showers and thunderstorms into the eastern half of South Central Texas. The front will be moving into a moist, conditionally unstable airmass. Dewpoint temperatures will be in the middle 60s to lower 70s. Forecast soundings show very high CAPE, but a stout cap. Convection should be ongoing as the front arrives and this cap may not matter. SPC has included a small portion of Burnet, Williamson, and Lee Counties in the Enhanced risk area with the Slight risk down to a Fredericksburg to New Braunfels to Hallettsville line and the Marginal risk from Kerrville to San Antonio to Kenedy. They expect a line of storms to be moving into our CWA late tonight and that damaging wind gusts will be the most likely threat with large hail also possible. The tornado threat is very low, but not zero. Models have slowed things down and the short term models are showing a line of storms moving into our northeastern counties sometime after midnight and moving through San Antonio by around 6 am and out our CWA by mid-morning. Convection should end quickly behind the front as drier air moves in. Winds will become breezy from the north during the afternoon. Winds will weaken during the evening as the pressure gradient relaxes. Clear skies, light winds, and cold advection will lead to low temperatures Thursday being below normal. LONG TERM (Thursday through Tuesday)... After a dry and pleasant Thursday, conditions get warmer and more humid with southeasterly winds. Temperatures will reach into the 90s on Friday with most areas near the triple digits by Sunday. Overnight temps will be warm as well, with lows in the 70s. The combination of heat and moisture will produce heat indices of up to 104 to our west along the Rio Grande Plains, and 100 to 102 in our metro areas of San Antonio and Austin. This trend continues into midweek next week. Another upper disturbance approaches by Wednesday, but with typical Day 7 model inconsistency, the forecast remains dry, and is likely to change over the next few days. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 69 82 55 84 59 / 50 10 0 0 0 Austin Bergstrom Intl Airport 68 81 51 84 57 / 50 20 0 0 0 New Braunfels Muni Airport 67 83 53 84 56 / 40 20 0 0 0 Burnet Muni Airport 66 79 52 83 57 / 50 - 0 0 0 Del Rio Intl Airport 69 87 59 91 63 / 0 - 0 0 0 Georgetown Muni Airport 66 79 53 83 58 / 60 10 0 0 0 Hondo Muni Airport 69 86 54 89 57 / 20 - 0 0 0 San Marcos Muni Airport 67 82 53 84 56 / 50 20 0 0 0 La Grange - Fayette Regional 69 81 54 84 57 / 60 40 0 0 0 San Antonio Intl Airport 69 84 55 86 58 / 30 10 0 0 0 Stinson Muni Airport 69 86 56 87 58 / 30 10 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term/Aviation...Treadway Long-Term...BMW
National Weather Service Hastings NE
953 PM CDT Tue Apr 28 2020 .UPDATE... Issued at 952 PM CDT Tue Apr 28 2020 Added some sprinkles in our eastern third of the CWA. We could actually get a stray shower or two, but probably not enough coverage to warrant actual POPs. && .SHORT TERM...(This evening through Wednesday) Issued at 215 PM CDT Tue Apr 28 2020 Secondary front is pushing through the area, ushering in widespread 45 MPH wind gusts. Showers are starting to develop in the cold air advection behind it. There is not much instability to work with, but a few isolated thunderstorms remain possible as well. More concerning is the potential for these showers/storms to mix down stronger winds to the surface. Latest model runs of the HRRR have backed off on wind speeds somewhat, but the potential still exists for some localized gusts in the 50-60 MPH range. As mentioned previously, the main timeframe for this would be now through roughly 8pm this evening. Surface winds will back off a bit this evening, but will pick back up after midnight thanks to stronger winds aloft on the backside of the upper trough. Although Wednesday won`t be as windy as today, it will still be fairly breezy. Gusts around 30 MPH will be common in the morning, but will gradually taper off in the afternoon. Highs have trended down just a bit for Wednesday, now ranging from the upper 60s to low 70s. For more information on the fire weather threat tomorrow, see the fire weather section below. .LONG TERM...(Wednesday night through Tuesday) Issued at 215 PM CDT Tue Apr 28 2020 Winds will drop off quickly Wednesday evening. Skies will also clear out as high pressure moves in, allowing for good radiational cooling. Currently, overnight lows are expected to be in the 38-42 degree range. For now, this would be just warm enough to avoid frost concerns, but it is something we will need to keep an eye on. Other than marginal fire weather concerns, Thursday and Friday will be relatively quiet days as we see increased ridging aloft and a return to southerly winds. Highs are still expected to return to the upper 80s and low 90s by Friday. The ridge begins to break down and upper level flow becomes more on Saturday, allowing a chance for showers and thunderstorms to return through the area. Periodic rain chances continue through the weekend and into early next week as a series of shortwave troughs move through. Hopefully this can bring some much-needed meaningful rain to the area. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday) Issued at 658 PM CDT Tue Apr 28 2020 Wind should quickly diminish at the surface this evening with loss of daytime heating. However, wind aloft will be relatively strong tonight, and will warrant LLWS. VFR conditions are forecast. && .FIRE WEATHER... Issued at 215 PM CDT Tue Apr 28 2020 Ongoing strong winds will continue the high fire danger threat this afternoon into this evening. In fact, the dry-air advection will keep RH values relatively low through the overnight hours. Maximum RH values may only rise to around 50 percent for southwest portions of the area. This will set the stage for another round of critical fire danger again on Wednesday. Winds will slowly decrease through Wednesday, but gusts will likely continue to be at least around 25 MPH through the afternoon. Minimum RH values of 15-20 percent are expected for areas near and southwest of a line from Lexington to Beaver City, NE. Therefore a Fire Weather Watch was issued for these areas. Luckily, we will see some recovery Wednesday night as high pressure moves in, but Thursday may be another near-critical day as winds shift back to the south and humidity drops back to the 15-30 percent range in the afternoon. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Fire Weather Watch from Wednesday afternoon through Wednesday evening for NEZ060-072-082. KS...NONE. && $$ UPDATE...Heinlein SHORT TERM...Mangels LONG TERM...Mangels AVIATION...Heinlein FIRE WEATHER...Mangels
Previous forecast discussion >
Steep low level lapse rates will be in place through the early
evening hours. Winds have already started to gust and will continue to do so through the early evening hours. This southwesterly flow has already allowed temperatures to climb into the 70s across all except portions of central Ohio where there is more cloud cover. There is an extensive cu field that has developed across northern portions of the forecast area. It is across this area where isolated to scattered shower activity is expected to develop for the late afternoon and early evening hours. There is a little bit of limited instability, however decided to leave thunder out at this time. Working into the overnight timeframe, expect a few spotty showers across the area, however many locations will remain dry for most of the overnight hours. Although wind gusts will decrease, expect winds to stay up through the overnight. This will allow for temperatures to only drop off into the middle to upper 50s. Towards the end of the near term time frame more widespread shower activity will approach the region. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... More widespread shower activity will work into the region at the start of the short term and overspread the region during the morning. With dry low level air in place to start and decent low level flow, expect winds to become gusty in advance and with the showers moving in. Some models are indicating as high as 50 mph with some of this activity. Increased wind gusts to 35 to upwards of around 45 mph, however did not go as high as 50 mph at this time. Will highlight wind potential in the HWO. There will be the potential for isolated strong to severe gusts, however at this time decided just to trend towards the higher gusts as low level lapse rates are not overly steep. There will be the potential for additional gusts into the afternoon hours as additional shower activity develops and moves into the region. There will be some concern for additional strong to severe gusts. CIPS analogs are showing a strong signal for at least some severe weather potential for Wednesday. There is limited instability during the day on Tuesday. Have a slight chance of thunder in with the precipitation chances. Working into Wednesday night, there will be additional shower activity as the upper level disturbance moves through. Although wind gusts will decrease from during the daytime hours, expect some additional gusty winds overnight. Although a little cooler airmass will be working into the region, with cloud cover across the region temperatures will only drop down into the middle 40s to around 50. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Large scale upper level low will have occluded with its surface low by Thursday morning. The large scale circulation along with embedded spokes of vorticity rotating around the center will bring showers to the region. It will be much cooler with temperatures being held down by clouds and rain. Highs will range from near 50 across west central Ohio to 50 to 55 elsewhere. These readings will be some 10 to 15 degrees below normal. For Thursday night into Friday, it will be a slow process in terms of how fast the large scale upper level low will progress east. We should see a decrease in the threat for showers through the period along with slow clearing trend from the west. After lows in the lower to mid 40s, highs will remain somewhat cool, especially east where clouds linger longer. Thus, highs are expected to range from near 60 west to the mid/upper 50s elsewhere. It looks like we should see a period of dry period Friday night into Saturday as high pressure briefly moves into the region. After lows in the lower to mid 40s, highs will rebound into the upper 60s to the lower 70s, which are fairly close to near normal values for early May. Models have indicated a consistent signal in terms of the next weather system to affect the Great Lakes and Ohio Valley. Short wave energy is forecast to dig southeast into the the region on Sunday, pushing low pressure and a cold front into the region. Thus, will continue with a chance of showers and thunderstorms for most of the region (southern areas will have a low likely probability at this time). It will be seasonably warm in the lower to mid 70s. Models are now showing more bona fide drying behind the front Sunday night into Monday as high pressure settles into the area. The latest forecast reflects this. Highs will cool down into the 60s. By the end of the extended period, a large scale trough will try to develop/dig into the region. At this time have brought in a chance of showers and thunderstorms on Tuesday. Highs again will be mainly in the 60s. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... VFR conditions are expected through the overnight hours, with thickening clouds that will gradually lower to below 6kft, and increasing chances for showers. Winds will be around 10-15 knots or less through most of the overnight period, but an increase with gusts of 20-25 knots is expected before 12Z. There will also be LLWS, as indicated in the KDAY/KILN/KCVG/KLUK TAFs. After 12Z, showers will become more likely, accompanied by occasional MVFR conditions. Also coming along with these showers will be increased wind gusts into the 30-35 knot range. Some isolated higher gusts may also be possible, especially between 12Z-17Z. Eventually, MVFR ceilings will settle into all of the TAF sites, with some potential for brief IFR conditions at KDAY/KCVG/KLUK during the mid to late afternoon. Chances for showers will also continue into the evening. OUTLOOK...MVFR ceilings will remain possible on occasion through Friday morning. MVFR conditions and thunderstorms will be possible on Sunday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Novak NEAR TERM...Hatzos/Novak SHORT TERM...Novak LONG TERM...Hickman AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Lake Charles LA
1042 PM CDT Tue Apr 28 2020 .DISCUSSION... Radar showing decaying MCS responsible for this afternoon and evening`s showers and thunderstorms now over the coastal waters. The next squall line of thunderstorms continues to stretch from N TX/SE OK/AR/MO/IL, or just say several states with watch boxes along and ahead of this system. This line of thunderstorms still expected to move southeast across E TX/LA overnight, with strong to severe thunderstorms associated with it. Most of the area remains in a slight risk, with an enhanced risk across SE TX north of I-10. With the rapid south-southeast trajectory of this line last clocked at 60 mph, wind and hail will likely be the main severe weather threat, but cannot rule out a possible tornado. Latest HRRR guidance puts this entering the northern portion of Inland SE TX/C LA by 3 AM and reaching the SE TX/SW LA coast by 5 AM, give or take an hour. For the forecast, tweaked precip grids bit for this evening to account for lingering showers/thunderstorms, and broke up precip grids by 3 hour increment`s between 1-7 am to show the progression of the squall line. After 7 AM, the line should be clearing the SC LA coast and moving across the remainder of the coastal waters. DML && .PREV DISCUSSION... /issued 621 PM CDT Tue Apr 28 2020/ AVIATION...A line of storms is currently stretched northeast from SE Cameron Parish across KARA. Light to moderate rain and occasional lightning is behind the line. Over the next few hours hours this convection will exit east and conditions will briefly improve before lower ceilings redevelop this evening and additional convection enters from the northwest late tonight. Winds will become SE this evening then SW late tonight and NW tomorrow behind a front. PREV DISCUSSION... /issued 431 PM CDT Tue Apr 28 2020/ DISCUSSION... Ongoing convection across SE TX into central/southern LA expected to continue slowly moving S/SE through the rest of the afternoon, with a decrease in intensity/coverage heading into early evening. This activity should remain sub-severe, though small hail and/or wind gusts up to 50 mph are possible in the stronger cells. In addition, owing to rather sluggish movement, cell mergers, and high atmospheric MSTR content, 1 to 2 inch rainfall totals over the course of an hour or so are possible as well, which could lead to some localized minor flooding. The degree/extent of convection this afternoon was not well anticipated, with convective development more extensive and farther south both this morning and this afternoon. The lead shortwave trof turned out to be a little stronger than depicted in model guidance yesterday, and coupled with ample moisture, steady moist inflow, and little convective inhibition, was sufficient to kick off convection that took advantage of at least marginal shear to organize into multicell clusters/lines. It is not altogether clear what if any impact the more substantial convection today will have on thunderstorm activity later tonight, but it is worth noting that short range guidance that has somewhat of a grip on current activity continues to show an extensive generally W-E oriented band of thunderstorms entering interior SE TX and Central LA in the 1 to 3 am time frame, then continuing to race south through the area reaching the coast by 5 to 7 am. SPC has increased the risk of severe thunderstorms, outlining the area to the N and W of a line from Nome to Mauriceville TX, on to Leesville LA within an enhanced risk, and the rest of the area in a SLGT risk. The main difference is greater risk of severe winds in the enhanced area, as that segment of the line is shown to both accelerate faster and remain more coherent/intense in CAM guidance. This is the primary severe weather hazard, along with large hail, and to a lesser extent tornadoes. There will also be an accompanying risk of locally heavy rainfall despite the expected quick southward progression, and should the convection materialize as advertised, this risk will be heightened by the antecedent rainfall observed today and early this evening. Rains should mostly wrap up my WED morning, though at least some activity may still be over the coastal waters and perhaps lower Acadiana. Otherwise, northerly winds behind the front will be ushering in drier and slightly cooler air, with near or just below seasonal normals expected WED night through THU night. No big changes made to the extended forecast, with a gradual increase in temperatures and humidity expected FRI, through the weekend, and into early next week. Little to no chance of rain expected until perhaps MON or TUE. 13 MARINE... Modest onshore flow will continue through tonight. Winds will subside Wednesday morning as the pressure gradient relaxes ahead of an approaching front. Numerous showers and thunderstorms are expected Wednesday morning along and ahead of this front. Some of these storms could be strong to severe with damaging winds and large hail. Precipitation will come to an end following the frontal passage late Wednesday. A brief period of light to modest offshore flow will follow the frontal passage Wednesday night into Thursday with an onshore flow returning to end the work week and start the weekend. 13 && .PRELIMINARY POINT TEMPS/POPS... AEX 63 78 51 77 / 90 40 0 0 LCH 64 81 56 79 / 90 90 0 0 LFT 64 80 54 78 / 90 100 0 0 BPT 68 81 56 79 / 80 90 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...Small Craft Exercise Caution until 7 AM CDT Wednesday for GMZ450- 452-455-470-472-475. && $$ PUBLIC...08
Area Forecast Discussion
National Weather Service New Orleans LA
644 PM CDT Tue Apr 28 2020 .AVIATION... Main concern for this forecast cycle is the broken line of thunderstorms currently moving through the area. The line currently is from roughly Tylertown, MS to Hammond to Donaldsonville moving SE. Main impacts to terminals ahead of this line ASD, MSY, NEW and HUM are gusty winds up to around 40 kt. Ceilings will drop down to MVFR to IFR. Additionally visibilities may be obscured due to heavy rainfall. Put best timing as a tempo group for these terminals. Behind this line of thunderstorms will be mostly light rain with maybe embedded tsra. Still monitoring a secondary line of thunderstorms possible in the early morning hours as well. -BL && .PREV DISCUSSION... /issued 422 PM CDT Tue Apr 28 2020/ SYNOPSIS... Mosaic radar showed convection from southwest Mississippi to southeast Texas. In addition, IR satellite imagery showed cloud top cooling over southeast Texas and southwest Louisiana. Latest surface analysis showed a 1024mb off the Georgia coast and 1004mb low over west Texas. Southerly flow was present across Texas and Lower Mississippi Valley. Surface dewpoints were in the 60s and 70s over east Texas, 60s over Louisiana, and 50s over Mississippi. Upper level analysis showed a short wave from northwest Mississippi to southeast Texas and clipper system over the northern and central plains diving southeast. Isotach analysis showed the northern stream jet of 120 knots from Montana to northern Colorado on the backside of the clipper. DISCUSSION... HRRR and RAP continue to show convection associated with the short wave pressing east southeast this afternoon and this evening. NAM12 and GFS showed lapse rates of 7.0 to 7.5 C/km from 700 to 500mb from southwest Mississippi to southwest Louisiana this evening. LCH sounding from 12z this morning showed a lapse rate of 8.6 C/km and surface base cape value 420j/kg. Southerly winds have modified instability values across east Texas and west Louisiana. Forecasted surface base cape values increase 600 to 800 j/kg this afternoon but this convection is driven by the short wave. As the short wave push east, expecting this convection to push east weakening before midnight. Wave over northern and central plains will continue to dive southeast and deepen the main trough over the mid Mississippi Valley overnight into Wednesday. An associated trough axis and frontal zone will push into the area early Wednesday. With the ongoing convection, cautiously looking at this second wave of convection along the front. Surface base cape values are expected 300 to 600 j/kg directly north and east of Lake Pontchartrain but pooling along this boundary with cape values 1000 to 2000 j/kg west of Lake Pontchartrain after midnight. Moisture will pool along the frontal with precipitable water values 1.8 to 1.9 inches. As a result, will maintain high rain chances with more showers and scattered embedded storms along the front early Wednesday. A few strong to severe storms in a squall line are possible with hail and strong to damaging wind gusts being the main factor but can not rule out an isolated tornado. Showers and storms will linger through Wednesday day period as rainfall amounts of 1 to 2 inches can be expected. Dry conditions are expected through Thursday through the weekend with warm conditions. AVIATION... Short range models are suggesting convection developing over southwest Louisiana tracking southeast affecting KBTR, KHUM, KMSY and KNEW between 23z today and 03z Wednesday. Will use tempo TS to cover this threat. Cigs will move into the area just before midnight at OVC030 and fall to OVC010 before daylight while sh/ts will also be noted as prevailing at NW terminals before daylight and all remaining terminals after daylight. Some of these TS could produce strong wind speeds as well. MARINE... Return flow will continue through Wednesday morning ahead of an approaching cold front. Winds will increase on Wednesday afternoon and Wednesday night especially behind the front as a moderate offshore flow once again returns to the coastal waters. Offshore flow will continue on Thursday and gradually lull by Thursday night remaining light but shifting around to a southerly direction over the weekend. && .PRELIMINARY POINT TEMPS/POPS... MCB 63 77 55 76 / 50 70 0 0 BTR 63 78 54 76 / 50 60 0 0 ASD 63 79 55 79 / 40 70 0 0 MSY 66 79 61 78 / 40 60 0 0 GPT 66 77 58 76 / 20 60 10 0 PQL 64 80 55 79 / 20 70 20 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Louisville KY
952 PM EDT Tue Apr 28 2020 .Forecast Update... Issued at 952 PM EDT Tue Apr 28 2020 An impressive line of storms erupted to our west earlier this evening and extends from Illinois to Oklahoma. The southwest portion of this line will dive southward into Texas and Louisiana overnight. The northeast section of the line will weaken as it slides southeast into an increasingly stable air mass. Still, an incoming 5H speed max rounding the base of the upper trough, increasing low level jet from the lower Mississippi Valley to the upper Ohio Valley, and an approaching cold front and possible outflow boundary will interact with precipitable waters climbing to 1.50". Though the HRRR has not been showing much activity over southern Indiana and central Kentucky overnight, will continue with high PoPs given the above, leaning more toward the slightly wetter RAP. && .Short Term...(This evening through Wednesday) Issued at 300 PM EDT Tue Apr 28 2020 ...A Stretch of Gusty Winds, Widespread Rain, and a Few T-Storms... A pair of upper lows over the north central U.S. this hour will merge into one closed low by daybreak Wednesday somewhere near the MO/IA/IL border. As it does so, a surface low pressure system, now near the IA/MN border, will deepen as it slowly wobbles eastward. As these features combine, and with surface heating over the MO/IL vicinity now, expect a long line of thunderstorms to develop in the 20-23Z time frame from northern IL southwest to central OK. Latest HRRR/3kNAM/WoFS all agree with this scenario. This line should push eastward this evening, approaching our western counties around midnight. As the night goes on, expect a low-level jet to develop out ahead of the deepening Midwest system. Convergence over this area should allow the line of storms coming in from the west to at least hold together enough for categorical pops by daybreak...though a nocturnal inversion should keep any severe winds aloft. Still, the gradient will tighten up ahead of this system, and expect some 25-35 mph wind gusts in the region by daybreak and for several hours into the morning. By late morning, convective temperatures look to be low enough to see additional showers/some storms develop closer to the actual cold front pushing eastward through the region. Given the cold dome of air coming with the upper level low passing by just to our north, would not be surprised to see some gusty conditions. Dry mid levels in the soundings also would give the potential for some small hail. Bottom line...enjoy the warm weather this afternoon...we go back to dreary and wet tomorrow. .Long Term...(Wednesday night through Tuesday) Issued at 300 PM EDT Tue Apr 28 2020 The long term will start off a bit dreary as light showers/drizzle persist for much of Thursday, as an upper level low grazes the region behind a departing cold front. Could also see some breezy winds throughout the day as the aforementioned low and its tight pressure gradient drift SE towards the Atlantic. Given the cooler airmass and cloudy skies in place, only have highs reaching the mid 50s to low 60s. Dry conditions look to return Friday and should prevail through Sunday morning, as sfc high pressure moves overhead. It`s also worth noting that temperatures will experience quite the rebound during this time, thanks to southwesterly winds and enhanced WAA. As such, expect afternoon highs to climb into the mid to upper 70s each day! Unfortunately, unsettled weather looks to return to the forecast Sunday afternoon, as an upper level shortwave and sfc cold front drift across the Mississippi Valley and encroaches upon the region. While light showers will likely begin in the afternoon, most models agree that best time for seeing widespread showers will occur late Sunday night through early Monday morning. In regard to the severe potential, a round of convection may certainly be possible, however, a decent amount of uncertainty still remains. For now, will continue to monitor trends and analyze severe parameters as they become more transparent in the coming days. Lastly, as we head into the new week, models hint that a potent system originating over the Pacific NW will dive SE and take aim at the Ohio Valley on Tue/Wed. However, given that this system is towards the end of the extended period, am not confident in any one solution, so have decided to continue with blended solution of PoPs at this time. && .Aviation...(00Z TAF Issuance) Issued at 731 PM EDT Tue Apr 28 2020 An approaching cold front will bring increasingly messy weather to the region for much of this TAF period. As we go through the overnight hours clouds will increase and lower, with widespread showers and embedded thunderstorms developing. Low level winds will increase and bring LLWS to the airports. Surface winds will also stay up and will be occasionally gusty. On Wednesday a pre-frontal trough will pass through in the morning followed by the cold front in the afternoon, causing SSW winds to shift to WSW, with the windiest and wettest conditions, and lowest ceilings, in the morning. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...13 Short Term...RJS Long Term...SSC Aviation...13
Area Forecast Discussion
National Weather Service Nashville TN
834 PM CDT Tue Apr 28 2020 .DISCUSSION... Amazingly nice evening across Middle Tennessee with current temperatures in the 60s to around 70 and low RH with dewpoints only in the 40s. Regional radar imagery shows an extensive line of thunderstorms from STL to SGF that will move southeast towards us overnight. Due to much less low level moisture in place across our area and thus a much more stable environment, these storms should weaken significantly as they approach and enter the forecast area a few hours after midnight. Therefore no severe weather is anticipated in our cwa, although some gusty winds are possible. Have tweaked grids and removed pops for the rest of the evening, and adjusted them significantly after midnight based on latest HRRR and CONSShort model timing. Additional showers and thunderstorms are expected to form Wednesday morning into the afternoon as a cold front sweeps through and higher low level moisture is advected into the area, and a few of these storms could be strong east of I-65 in the afternoon prior to the front exiting. && .AVIATION... 00Z TAF DISCUSSION. VFR and gusty SW winds continue. A few showers could impact CSV after 06z, followed by a decaying line of SHRA/TSRA at CKV/BNA/MQY after 08-09z. Redeveloping SHRA/TSRA after 15z may impact the terminals, with the greatest likelihood of reduced VIS/CIGs at CSV after 18z. Behind a frontal passage around 21z, winds become westerly. && .PRELIMINARY POINT TEMPS/POPS... Nashville 60 69 50 63 48 / 80 80 30 30 10 Clarksville 59 67 49 62 47 / 80 80 30 20 10 Crossville 54 63 45 55 42 / 40 90 60 70 20 Columbia 59 69 49 63 46 / 80 80 20 30 10 Lawrenceburg 59 69 49 63 46 / 70 80 20 30 10 Waverly 59 69 49 63 47 / 80 80 20 20 10 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Shamburger AVIATION........Schaper
Area Forecast Discussion
National Weather Service Pocatello ID
200 PM MDT Tue Apr 28 2020 .SHORT TERM...Tonight through Thursday night. Above normal dry spring conditions are expected into Wednesday as upper ridge works east to East Idaho. By Wednesday afternoon southwest flow increases ushering moisture into the region. Very warm temperatures in place will help increase instability for generally isolated thunderstorms by early evening. Guidance consensus still targets Wednesday for warmest day of the week with some places approaching or exceeding 80 degrees across the Eastern Magic Valley and Lower Snake Plain. Instability looks greatest on Thursday so have chance/scattered thunderstorms most places. Will also be breezy to windy Thursday and continued quite warm though a few degrees cooler than the highs Wednesday. Given overnight cool temperatures, heat risk is unlikely this early in the season. DMH .LONG TERM...Fri through next Tue night. Fri temperatures will be colder in the wake of the Thu trough and surface front. By Sat afternoon the next trough is at the coast and it is already affecting eastern and central Idaho with showers and thunderstorms. The showers and afternoon/evening thunderstorms continue through Sun night with the upper level negative tilt trough crossing through the Gem State during that time. Expect thunderstorms and showers, and there could be some severe weather with the negative tilt trough, as it normally has upper level diffluence and enhanced ageotrophic wind due to the speed max aloft. Increased cloudiness brings temperatures down, and snow may return Sun night to the mountains. More showers and thunderstorms in the unstable air behind the trough and cold front for Mon due to unstable conditions. Maybe a return to normalcy for Tue. The timing has slipped at little for the onset of wet weather, with more now on Sun night rather than Sun. The GFS continues to be wetter, and the NBM, especially for Mon to the end, had fairly high PoP and had to be toned down, but at least it was now matching the cloud cover better. Messick && .AVIATION...No impacts due to barely there cloudiness and unlimited visibility with light wind. The only oddity is that northwest wind aloft over KSUN, once it mixes down, will challenge the usual southeast wind during the afternoon. At this time have put in nortwest wind, but confidence in direction is low; am basing this on the HRRR which usually does will with direction. Messick && .HYDROLOGY...Warm temperatures this week will continue to enhance mid and upper level snow melt across the region. High flows are expected to continue or even increase especially on smaller creeks and streams across East Idaho. Willow Crk and Blackfoot River continue to run at or very near flood stage, and are expected to fluctuate around flood stage for the next several days. Thus have continued the warning for Willow Crk and the advisory for the Blackfoot River, with the understanding that at any time this week those products can flip/flop based on the current waterway conditions. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Pueblo CO
810 PM MDT Tue Apr 28 2020 .UPDATE... Issued at 805 PM MDT Tue Apr 28 2020 Updated forecast to expire the Red Flag warning which was in effect over parts of the region. /Hodanish && .SHORT TERM...(This evening through Wednesday) Issued at 301 PM MDT Tue Apr 28 2020 Red flag conditions verifying over the San Luis Valley at mid- afternoon, where N-NW winds were gusting 25-30 kts at most observing locations. Over the plains, surface cold front has been rather slow to push south and westward, with critical fire weather conditions limited to portions of northern/eastern El Paso County and the southeast plains east of La Junta. HRRR still shows boundary pushing all the way west to the mountains by 00z, leading to a period of 20g30kt N winds through most of the current Red Flag Warning area into the evening. As a result, will leave current highlight untouched and allow it to continue until expiration at 02z. Winds then diminish overnight and into Wed morning, as high pressure builds in at the surface and aloft, leading to seasonably cool min temps at many locations. On Wed, much lighter winds all areas, as upper level ridge slides toward Colorado, with max temps running just slightly above late April averages. .LONG TERM...(Wednesday night through Tuesday) Issued at 301 PM MDT Tue Apr 28 2020 Wednesday night into Friday...The upper-level ridge axis is expected to edge slightly eastward by around midday Thursday, centering it over Colorado. The ridge then remains in place into Friday, resulting in a boost in temperatures to near record highs for both Thursday and Friday. Highs are expected to reach the upper 80s into lower 90s across the plains with Friday being the warmer of the two days, while the high valleys are expected to reach the upper 70s to mid 80s both days. The ridge begins to flatten out during this time as well, which is expected to bring somewhat stronger westerly flow aloft to the region. The stronger westerly flow is anticipated to bring increased surface winds and drier conditions to the area, likely creating critical fire weather conditions, especially for the San Luis Valley where winds are expected to be a bit stronger than on the plains. Therefore, have decided to issue a Fire Weather Watch for the San Luis Valley for Thursday afternoon. Friday also appears to be a day that will require fire weather highlights, but have decided to hold off for the time being. Isolated convection over the mountains also remains possible each afternoon. Saturday into Monday...A few disturbances are anticipated to bring a chance of precipitation each afternoon and evening to areas generally along and east of the central and eastern mountains, with Saturday having the best chance for showers and thunderstorms. Deterministic and ensemble models are both in fairly good agreement that a shortwave trough is progged to propagate across the region Saturday into Sunday morning, bringing increased precipitation chances to the region, especially the Palmer Divide and plains. However, ensembles are showing a little bit of spread between their individual members, indicating a little lower confidence in the forecast, mainly with the timing of when the trough moves through the region. That being said, some stronger, potentially severe, thunderstorms over the far eastern plains appear to be possible Saturday afternoon and evening as CAPE values up to the 1000-1500 J/kg range are forecast in some locations, with bulk shear values forecast to be about 40-50 kts. Additional chances of precipitation for the Palmer Divide and into portions of the far eastern plains return Sunday evening and again Monday evening, but the best chances for precipitation remain north of our region. Meanwhile, dry and breezy conditions are expected over the San Luis Valley, bringing the potential for critical fire weather conditions again each afternoon. Temperatures are also expected to cool slightly due to easterly surface flow with highs generally in the 80s across the plains, and 70s in the high valleys. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 301 PM MDT Tue Apr 28 2020 VFR at all taf sites tonight and Wed. Still expect a period of breezy N-NW winds at KPUB and KCOS from late this afternoon into the evening, with gusts 25-30 kts until 04z-06z. At KALS, N winds gusting 25-30 kts will continue into the evening, before diminishing 02z-04z. Lighter winds expected all terminals on Wed. && .PUB WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Thursday afternoon through Thursday evening for COZ224. && $$ UPDATE...HODANISH SHORT TERM...PETERSEN LONG TERM...CARLBERG AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
808 PM EDT Tue Apr 28 2020 .UPDATE... Another quiet day across the region with high pressure centered now over the Atlantic Ocean. With this shift, winds have become more easterly, leading to a modification of the air mass over us. This will result in a milder night, with temperatures falling into the 60s area-wide and highs warming in to the mid and upper 80s tomorrow afternoon. No updates needed to the ongoing forecast. && .AVIATION... VFR conditions are expected through the forecast period. East/southeast winds will become south and then southwest through Wednesday. && .MARINE... High pressure centered to the northeast will keep an east to southeast wind flow in place through tonight, with wind speeds reaching cautionary levels. Winds will diminish in the morning and then become more south to southwest through the afternoon. The next cold front will move through the area Wednesday night into Thursday, with showers and thunderstorms possible. Winds behind the front will become north to northwest for Friday into the weekend, with pleasant boating conditions expected. && .Prev Discussion... /issued 249 PM EDT Tue Apr 28 2020/ DISCUSSION... Current RAP analysis shows weak upper level ridging across the Gulf of Mexico while a couple subtle shortwaves have been helping to fire off late morning and early afternoon convection across the ARKLATEX region. At the surface, high pressure has now slid off to our northeast and effectively choked off the cooler/drier airmass that we received yesterday as easterly winds have finally returned to the area. Ample sunshine will heat things up to the mid/upper 80s this afternoon with near average lows tonight (in the 60s). A large and potentially significant wind event will occur across parts of the plains this evening into tonight. This convective system will be routed downstream along and ahead of a cold front as a deep trough digs across the Middle Mississippi Valley tomorrow and an area of low pressure forms near the Great Lakes. Out ahead of this front, our flow will shift out of the southeast leading to a warming and moistening environment. Latest guidance has the front and associated convective activity quickly moving into the Panhandle and Big Bend regions tomorrow night, reaching Levy county near or just after midnight. The front will gradually work south across our area through the first half of Thursday and produce showers and thunderstorms. Some of these storms will run the risk of producing damaging wind gusts. At the moment, shear and instability is only marginally conducive for maintaining a severe line into the Nature Coast. Kinematics and thermodynamics suggest more favorable conditions for robust convection farther south along the I-4 corridor during the late morning hours on Thursday where MLCAPE and 0-6km shear approach 500-1000 j/kg and 30 knots, respectively. Early CAM guidance seem to generally support this thinking at the moment. Meanwhile, pre-frontal storms are likely to fire up tomorrow evening across the far eastern interior and east Central Florida during the late evening/midnight hours along an area of enhanced convergence. However, overall coverage in our area will remain relatively low for our eastern counties. Once the front moves through, the drier post- frontal airmass will subsequently halt our rain chances through the remainder of the period... While not necessarily as pleasant as we witnessed on Monday, weather on Friday will be cooler and drier after the passage of the cold front with high pressure settling in to our northwest. While the lower dewpoints will hang around for a couple of days, temps will warm efficiently on Saturday courteous of strong daytime mixing. By Sunday, we will see temps climb up to around 90 with increasing humidity. By Monday and Tuesday, expect ample sunshine to provide us with a hot and humid day as low 90s will be prevalent and dew points climb into the mid 60s to near 70 degrees. Nevertheless, high pressure and little atmospheric moisture will keep rain free and mostly clear conditions into the first half of the week. AVIATION... VFR conditions for the period with prevailing easterly winds, except at coastal terminals where they may experience a wind shift through the afternoon as a weak sea breeze develops right along the coast. Tomorrow, winds will slowly veer from the east to southerly, becoming SSW by evening. MARINE... High pressure off to our northeast over the Atlantic Ocean will keep easterly winds in place (with the exception of onshore seabreeze) through this evening before they shift to out of the southeast and approach cautionary headlines overnight. Winds will gradually become more southerly tomorrow afternoon. The next cold front will move through the region Wednesday night into Thursday, with showers and thunderstorms out ahead and along the front. A few of these storms may be strong and produce hazardous winds for vessels. Winds will turn to the north to northwest behind the front for Friday with pleasant, rain free boating conditions heading into the weekend. FIRE WEATHER... Localized spots will see critical RH through the remainder of the afternoon. However, winds will preclude any significant fire weather concerns. Moderate southerly transport winds and strong daytime mixing will lead to high dispersions tomorrow, especially across inland areas north of I-4. A cold front will push through the area late tomorrow night into Thursday with showers and thunderstorms, some of which may produce gusty outflow boundaries. && .Preliminary Point Temps/PoPs... TPA 65 87 71 81 / 0 0 50 70 FMY 65 89 72 86 / 0 0 20 50 GIF 62 87 68 82 / 0 10 30 70 SRQ 64 85 71 83 / 0 0 40 60 BKV 60 89 67 81 / 0 0 50 70 SPG 67 83 71 82 / 0 0 50 70 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ UPDATE/AVIATION/MARINE...05/Carlisle Previous Discussion...Norman